my itunes songs are playing up

Hello zarnoss,

Thank you for providing the details of the issue you are experiencing with music in iTunes and on your devices. In my experience, this happens when the song doesn't download completely:

Occasionally, if a song purchased from the iTunes Store on a Mac or PC was not downloaded completely, the song may not play back fully. The song may abruptly stop during playback, and iTunes may start playing the next song in your library or playlist.

Songs in iTunes may not play back completely

http://support.apple.com/kb/TS4357

In a situation like this, I recommend deleting the problematic songs and redownload the songs from your past purchases.

Follow these steps to delete the song from iTunes:

Delete an item from your library

1. Click the item to select it, and press the Delete key.
2. Click Delete Item.
3. Do one of the following:
   • Remove the item only from your iTunes library: Click Keep File.
   • Delete the item from your computer: Click Move to Recycle Bin. The item is removed the next time you empty the Recycle Bin.

You can find the full article here:

iTunes 11 for Mac: Delete songs, playlists, or other items

http://support.apple.com/kb/PH12159

Next, you can follow the steps to redownload the songs to iTunes in this article:

iTunes 11 for Mac: Download previous purchases from the iTunes Store

http://support.apple.com/kb/PH12283

Once you have downloaded the songs again, you can resync them to your devices.

If you are still not able to play the songs fully after redownloading them, you can report an issue with this purchases using the steps in this article:

How to report an issue with your iTunes Store, App Store, Mac App Store, or iBookstore purchase

http://support.apple.com/kb/HT1933

Best,

Sheila M.